Five people fell through three-inch thick ice in West Addison, Vermont earlier this month. Luckily they were all pulled to safety. The chart below provides some guidance on necessary ice thickness for various activities but there is no such thing as "safe ice".
The safety of ice varies depending on a combination of factors including,thickness, temperatures over a period of time and on the day, depth of water under the ice, size of the water body, local weather fluctuations, and the extent of the ice. Ice on a given water body doesn’t freeze or thaw at a uniform rate. It can be thick in one spot and dangerously thin only a few steps away. New ice is usually much stronger than old ice. Direct freezing of still water makes stronger ice than that formed by melting snow, refrozen ice, or ice made by water bubbling up through cracks and freezing on the surface. Clear blue/black ice is stronger than milky white ice. Ice near the shore is weakest. The shifting, expansion and buckling action of the lake or stream over the winter continually breaks and refreezes ice along the shoreline. Protruding logs, brush, or docks can absorb heat from the sun and weaken the surrounding ice.
To ensure a save trip on the ice take the following precautions:
- Always observe ice first and test it before venturing out.
- Never go onto ice alone, let people know of your plans and timeframe, and dress for the conditions.
- Wear a life vest or some form of flotation device, bring claws or an ice-pick, and take a spare set of warm, dry clothes in a waterproof bag.
- Use an auger to test ice thickness.
January 31, 2013